Non-flammable paper for speaker cones

ABSTRACT

A non-flammable paper for speaker cones is prepared by adding (1) chlorinated polyolefin having a molecular weight of from 500 to 40,000 and a chlorine content of from 40 to 75 weight percent, or (1)&#39;&#39; bromine-containing chlorinated polyolefin having a molecular weight of from 500 to 40,000, a chlorine content of from 10 to 30 percent by weight and a bromine content of from 60 to 80 percent by weight and (2) antimony trioxide into paper pulp. The paper for speaker cones thereby produced has a good non-flammable property, without losing good sound-reproducing characteristics because it has reduced hygroscopicity and increased metal protecting properties.

limited Statee ?ater1t Nakazawa et al.

[ Sept. 23, 1975 [54] NON-FLAMMABLE PAPER FOR SPEAKER 3,436,494 4/1969Bozak 181/171 CONES 3,560,441 2/1971 Schwarcz et al 252 81 3,624,028 111971 252/81 Inventors: Masahiko Nakalawa; Shizuo 3,738,958 6/1973 Paul252/81 Nakamura; Mutumi Nakayama, all of Tokyo Japan Primary Examinerstephen J. Tomsky Assignee; Asahi Denka Kogyo K K', Tokyo Attorney,Agent, or FirmWoodhams, Blanchard and Japan Flynn 22] Filed: July 17,1974 [57] ABSTRACT [21] Appl. No.1 489,156

A non-flammable paper for speaker cones is prepared by adding (1)chlorinated polyolefin having a molecu- [3O] Forelgn Apphcaton PnontyData lar weight of from 500 to 40,000 and a chlorine con- July 19, 1973Japan 48-81162 tent of from 40 to 75 weight percent, or (1)brominecontaining chlorinated polyolefin having a molecular US s 6weight of from 500 to 40,000, a chlorine content of [51] Int. Cl. .1610K 13/00; H04R 7/00 from 10 to 30 percent by weight and a bromine con-Field Of Search 52/81; 1 s tent of from 60 to 80 percent by weight and(2) anti- 18l/l70, 6 mony trioxide into paper pulp. The paper forspeaker v cones thereby produced has a good non-flammable [56]References Cited property, without losing good sound-reproducing UNITEDSTATES PATENTS characteristics because it has reduced hygroscopicity1,759,387 5/1930 BatehOlIS 181/170 and increased metal ProtectingProperties- 2,4l6,447 2/1947 Lau hlin et al.. 162/159 3,092,537 6 1963Bra dts 162/159 9 Clams 2 Drawmg Flgures PQlOlQ I H- AQT US atent Sept.23.,1975

EXAMPLE 1 COM PAPATIVE EXAMPLE 1 SOUND PPESSURE (ab) I00 Z00 500 I0002000 500010000 FREQUENCY (CYCLES PER SECOND) i PEIOQ 1 NON-FLAMMABLEPAPER FOR SPEAKER CONES BACKGROUND OF THE INVENTION 1. Field of theInvention This invention relates to a loudspeaker having a diaphragm orspeaker cone made of a special non-flammale paper. Particularly, thisinvention relates to a paper for speaker cones having a goodnon-flammable property and good sound-reproducing characteristics.

This invention also Description of the Prior Art speaker cones which iscapable of maintaining its strength for a long period of time because itpossesses extremely reduced hygroscopic and increased metal protectingproperties.

2. Description of the Prior Art In the past, paper made of cellulosicfibers has been used as the material for making speaker cones because ofits advantages such as its relatively low density, high Youngs modulus,high propagation velocity of longitudinal waves, moderate vibrationloss, etc.

However, such conventional paper is flammable and therefore speakercones made of such paper without using additives, such asfireretardants, are insufficient as non-flammable speaker cones nowrequired in the world, especially in the United States.

Furthermore, since paper is hygroscopic and low in metal protectingproperty, changes of the humidity of the ambient air, etc. causedecreases in strength and deformation of speaker cones, thereby injuringtheir sound-reproducing characteristics.

In order to minimize or eliminate the above-mentioned disadvantages,much work has been done. For example, fire-retardants such as thefollowing organic phosphorous compounds, halogenated organic compoundsand inorganic compounds have been used as additives for imparting topaper a non-flammable property. Such organic phosphorous compoundsinclude tricresyl phosphate, diphenylcresyl phosphate, diphenyloctylphosphate, trichloroethyl phosphate, tributyl phosphate, triphenylphosphate, tris(dichloropropyl) phosphate, tris(dibromopropyl)phosphate, chlorophosphonate, bromophosphonate, phosphorus-containingpolyols and phosphonitrile chloride. Representative halogenated organiccompounds are chlorendic acid, perbrominated polyols, tetrabrominatedphthalic anhydride, tetrabrominated bisphenol A, tetrachlorinatedphthalic anhydride, decachlorobiphenyl, chlorinated paraffin, polyvinylchloride, polyvinylidene chloride, etc. Further, representativeinorganic compounds are alkali metal or alkali earth metal salts ofphosphoric acid and boric acid, etc.

However, the addition of the above-mentioned fireretardants cannotimpart a sufficient non-flammable property to paper. Moreover, thesefire-retardants are hygroscopic and therefore cause variations of soundreproduction caused by the decrease in strength and the deformation ofthe speaker cones due to variations in ambient humidity. Similarphenomena are caused by heat applied during processing. Further,above-mentioned halogenated organic compounds are corrosive to metalsand therefore cause the corrosion of the parts of speaker cones madefrom metals due to dehydrohalogenation.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a graph showing therelationship between the frequency and the sound intensity of speakercones.

2 FIG. 2 is a sectional view of a typical conventional loudspeaker, thecone of which can be made of the special paper in accordance with thisinvention.

SUMMARY OF THE INVENTION We have discovered a non-flammable speaker conecapable of overcoming the above-mentioned disadvantages.

The speaker cone of this invention has a good nonflammable property; andit possesses good soundreproducing characteristics.

It is an object of this invention to provide a speaker cone having agood fire-retardant property, as well as good sound-reproducingcharacteristics.

Another object of this invention is to provide a speaker cone capable ofmaintaining its strength for a long period of time because of itsextremely reduced hygroscopicity and increased metal protectingproperties.

The physical shape and size of the speaker cone is not critical,according to this invention. The speaker cone can be of any suitableshape and size in accordance with conventional practices in theloudspeaker art for the use of paper speaker cones or diaphragms, andthe invention does not pertain to any improvement in such physicalfeatures.

In order to make clear the overall construction of a typicalloudspeaker, there is illustrated in FIG. 2, a prior art loudspeakerconstruction (US. Pat. No. 3 436 494) and illustrating the shape of onerepresentative speaker cone. The loudspeaker comprises a housing 2having a permanently magnetized pole piece 4 and a core 6 with a spacefor receiving a voice coil 8 of a cone-shaped diaphragm or speaker cone10. The voice coil 8 has electrically conductive wires 12 wound aroundthe exterior surface thereof. The pole piece 4 and the core 6 provide amagnetic flux in the voice coil aperture 14 and AC electric signalsconducted through wires 12 generate a second magnetic flux. Theinteraction of the two magnetic fluxes induces axial movement of thevoice coil to which the speaker cone 10 is attached. Speaker cone 10 issupported by a compliant annulus 13 at the top and bottom.

The speaker cone 10 can be made of the special paper in accordance withthis invention.

It will be understood, however, that the invention is not limited to thespeaker cone of the shape illustrated in FIG. 2 and that the inventioncan be incorporated into speaker cones of various shapes and sizes inaccordance with the conventional practice in the art of loudspeakersusing paper speaker cones and diaphragms.

The speaker cone of this invention is made of cellulosic fiber paper.The paper contains as essential additive constituents uniformlydistributed in the cellulosic fibers, (1) chlorinated polyolefin powderor (1) bromine-containing chlorinated polyolefin powder and (2) antimonytrioxide.

The preferred examples of chlorinated polyolefins are chlorinatedpolyethylene, chlorinated polypropylene and chlorinated rubber, whereinrubber means natural or synthetic rubber. Such synthetic rubber includespolyisoprene rubber, polyisobutene rubber, butyl rubber, SB rubber,polybutadiene rubber, neoprene rubber and nitrile rubber, and the mostprefera ble is polyisoprene rubber. These chlorinated polyolefinmaterials such as chlorinated polyethylene, chlorinated polypropyleneand chlorinated rubber are conventionally produced as follows.

A starting material of polyethylene, polypropylene or natural orsynthetic rubber is dissolved in one or a mix ture of two or morehalogenated hydrocarbon solvents and then it it is chlorinated byintroducing a gas containing at least 80volume percent of chlorine, andwhich can contain more than 0.1 volume percent of oxygen and/or ozone,at l7070 C, preferably 4060C, in the presence of mineral acidscontaining water and radical initiators, whereby to form a reactionmixture containing chlorinated polyolefin having a chlorine content offrom 40 to 75 weight percent. The chlorinated polyolefin powder having amolecular weight of 500 to 40,000 and preferably, a particle size ofmore than 300 mesh and less than 80 mesh, is obtained by steamdistillation of the reaction mixture or precipitation in water. If theneed arises, pulverization can be carried out after steam distillationor precipitation in order to adjust the particle size of the chlorinatedpolyolefin powder.

The halogenated hydrocarbon solvents used for dissolving said startingpolyolefin must be inert during the chlorination step. Examples of thepreferred solvents are halogenated lower aliphatic hydrocarbons such asmethylene chloride, chloroform, carbon tetrachloride, trichloroethyleneand tetrachloroethylene, and halogenated aromatic hydrocarbons such asmonochlorobenzene and dichlorobenzene. The most preferred and practicalsolvent is carbon tetrachloride because of the solubility of thepolyolefins therein, the ease of solvent removal after chlorination, andthe closeness of its boiling point to that of the reaction temperature.

The amount of polyolefin dissolved in the halogenated hydrocarbonsolvent is in the range of l to 20, preferably 3 to 10, percent byweight.

The preferred mineral acids are phosphoric acid, sulfuric acid,hydrochloric acid, etc. The concentration thereof in the aqueous acidsolution is usually more than 0.1 N. The amount of aqueous mineral acidsolution added to the solution of polyolefin in the halogenatedhydrocarbon solvent is from 0.5 to 3.1, preferably l to 2, parts byweight, per one part by weight of polyolefin.

The addition of mineral acid to the chlorination reaction system is notalways essential during the initial stage of the chlorination reaction,because the hydrogen chloride gas by-produced during the chlorinationbecomes dissolved in the water added at the initial stage to formaqueous hydrochloric acid solution. However, the concentration of themineral acid aqueous solution must be more than 0.1 N during the finalstage of the chlorination reaction.

Further, the radical initiators used in this reaction arenitrogen-containing compounds (azo compounds) having the followingformula:

R I R" R C N N C R'" l X X wherein R, R, R" and R, which can be the sameor different, are alkyls having one to four carbon atoms, and X is CN orC0 R, wherein R' is alkyl having one to four carbon atoms.

Examples of preferred initiators are shown in the following formulas.

4 (fH C|IH CH c| N r: cs

CN CN 3 $3 CH (I N N (I: CH

c0 CH 00 cm The amount of these azo compounds such asazobisisobutyronitrile, added to the reaction system is from 0.01 to1.0, preferably 0.1 to 0.5, percent by weight, based on the weight ofsaid polyolefin. Furthermore, the chlorine gas used for chlorinating thepolyolefins in the halogenated hydrocarbon solvents can be supplied inadmixture together with oxygen and/or ozone. Howex er, the gas mixturemust contain at least volume percent of chlorine. The oxygen employedcan be the oxygen gas industrially produced by air fractionation ofgaseous mixtures of oxygen together with inert gases such as nitrogenand carbon dioxide, or air. Ozone, produced industrially for example bycorona discharge, can also be used together with the chlorine gas.

The presence of oxygen and/or ozone in the gas remarkably stabilizes thechlorinated polyolefins produced in the co-presence of said mineralacids and azo compounds in the reaction system.

When the oxygen and/or ozone content of the chlorinecontaining gas isless than 0.1 volume percent, the stabilizing effect of oxygen on thechlorinated polyolefin cannot be observed. However, the upper limit ofthe oxygen and/or ozone content of the chlorine-containing gas is 20volume percent in order to maintain the chlorine content of the gas highenough to highly chlorinate polyolefins from the economical point ofview.

The preferred range of oxygen and/or ozone content is 0.1 to 10 volumepercent.

The oxygen can also be supplied in the form of air. Thus, the reactiongas can contain nitrogen as a nonreactive diluent, provided that thechlorine content of the gas is at least 80 volume percent.

In the case of mixing oxygen and/or ozone and/or air into chlorine,either of the following two methods can be adopted. One is to introduceinto the reaction system a gas mixture obtained by introducing oxygenand- /or ozone and/or air into the chlorine stream and mixing themuniformly therein. Another method is to introduce the chlorine gas,oxygen and/or ozone and/or air separately and then mix them in thereaction system.

Bromine-containing chlorinated polyolefins are also effective for thepurpose of this invention. These brominecontaining chlorinatedpolyolefins are produced in such a way as disclosed in the JapanesePatent Publication No. 49-8952. The water suspension of the polyolefinslisted above is reacted with a brominating agent and chlorine gas togive a bromine-containing chlorinated polyolefins.

The preferred example is a bromine-containing polyolefin having achlorine content of from 10 to 30 percent by weight and a brominecontent of from 60 to 80 percentv In the past, powders of chlorinatedpolymers have been obtained by either direct pulverization of the solidpolymers or the removal of solvent from solvent solutions of thepolymers by steam distilling, precipitating or spraying the reactionsolution. The powder of chlorinated polyolefins used in this inventionis obtained most preferably by removing the solvent from the reac- 6 Theamount of chlorinated polyolefins added to the pulp is from 10 to 50,preferably 20 to 40, parts by weight, per 100 parts by weight of fibers.The preferred fixing agents are polyacryl amides, modified epoxy restionsolution by means of steam distillation or precipi- 5 ins, starches,polyethylene imines, polyethylene oxides, tation into water. Ifnecessary, pulverization can be carpolyvinyl alcohol, ethylene-vinylacetate copolymer, ried out after said solvent removal to adjust theparticle and carboxymethyl cellulose, the amount of antimony size.Chlorinated polyolefins obtained by steam distillatrioxide added to thepulp is from 5 to 40, preferably 10 tion are macroscopically thin leafor scale-like powders to 30 parts by weight, per 100 parts by weight offibers. of low bulk density. 10 Further, the amount of fixing agentadded is from 1 to Chlorinated polyolefin powders obtained by precipi-5, preferably 3 to 5, parts by weight, per 100 parts by tation innon-solvents, for example water, are macroweight of fibers. scopicallyglobular or ellipsoidal powders. These latter The preferred coagulatingagents are polyacrylpowders have more uniform particle sizes, comparedamide, aluminum sulfate, polyaluminium chloride, with powders obtainedby the other methods, and are, polyethylene imine, modifiedpolyamide-epichlorohytherefore, more preferable for use in thisinvention. drin resin, natural gum and the amount added to the Theparticle size of chlorinated polyolefins in this inpulp is from 0.01 to0.1, preferably 0.05 to 0.08, parts vention is preferably more than 300mesh size and less by weight, per 100 parts by weight of fibers. than 80mesh size. This invention provides a non-flammable speaker Anotheressential constituent present in the paper of come capable ofmaintaining its strength for a long perthe speaker cone, namely, (2)antimony trioxide is also iod of time because of its extremely reducedhygroemployed in the form of a powder of preferably more scopicity andits improved metal protecting property. than 300 mesh size and less than80 mesh size. The In order to obtain the above-mentioned effects, thespeaker cone of this invention is prepared in the'followmolecular weightand the chlorine content of chlori ing way. nated polyolefins must befrom 500 to 40,000 and from The preparation of the paper pulp fibers canbe car- 40 to 75 weight percent, respectively. When these fearied out inaccordance with conventional techniques. tures deviate from theabove-stated limited values, the These fibers are beaten with water toform a pulp, also objects ofthis invention cannot be achieved. Forexamin accordance with conventional papermaking techple, the addition ofchlorinated polyolefins having niques. The beaten pulp is thoroughlymixed with dyes, lower molecular weights and chlorine contents than thepigments and paper strengthening agents, and with the above-mentionedranges does not impart sufficient chlorinated polyolefins and antimonytrioxide in a non-flammability to the speaker cones, it causesstickibeater, in the same manner as is conventional for sizing ness ofthe speaker cones and a decrease of the sizing paper. These additivesare precipitated on the fibers by degree. adding a precipitating andfixing agent such as alumi- A preferred example of the preparation ofchlorinum sulfate, as is conventional. Further, the use of natedpolyolefins, an essential constituent of this invenother additives suchas coagulating agents is extremely tion, is as follows: effective. Intoa reaction vessel equipped with a stirrer, a chlo- The pulp-watersuspension is poured into a porous rine introducing tube, a thermometerand a condenser, mold to form a paper product in the form of a speakerare charged 60 parts (the term parts employed cone. Then, thespeaker-cone-type paper product is therein refers to parts by weight) ofpolyethylene dried to give a speaker cone. In some cases, the speaker(Trademark Sumikathene G 801 melt index 20) and cone can be shaped bycompression molding. 1140 parts of carbon tetrachloride. After they areThe preferred cellulosic fiber pulps used for the prostirred at refluxtemperature for 2-3 hours to dissolve duction of the speaker cone inthis invention are said polyethylene, 0.3 part of azobisisobutyronitrilebleached sulfate pulps of soft woods and hard woods (AIBN, 0.5 weightpercent, based on polyethylene) is and bleached or non-bleached sulfatepulps of mixtures added and an oxygencontaining chlorine gas is introofsoft and hard woods. duced. When 256 parts of chlorine is introducedover a The fiber concentration in the beaten pulp (water period of 7hours, the reaction is stopped and the reacsuspension of fibers) is from0.01 to 0.1, preferably tion mixture is steam distilled to givechlorinated poly- 0.03 to 0.07, percent by weight. Further, as paperethylene powder (CPE-l having a chlorine content strengthening agentsthere can be used known conven- 69.0 weight percent, a molecular weightof 3,000 and a tional agents, such as starch, natural gum, syntheticparticle size of 200 to 220 mesh. CPE-Z, CPP 1 CPP-2, paste,polyacrylamide, ureaformaldehyde resins, epoxy CR-l and CR-2 areproduced in a similar way as in the resins, polyethylene imine,polyethylene oxide and mixproduction of CPE1. Their chlorine content,molecutures thereof. The amount of paper strengthening agent lar weightand particle size are shown in Table 1. added to the pulp is from 0.1 to5 parts by weight, per 100 parts by weight of fibers.

TABLE 1 CPE-l CPE-2 CPP-l CPP-2 CR-l CR-2 chlorinated polyethylenechlorinated polypropylene chlorinated rubber Chlorine content 69.0 45.871.0 59.5 68.5 55.3 Molecular weight 3,000 21.000 5,000 12,000 5,00025.000 Particle size (mesh) 200-220 -100 280-300 -120 -135 85-105 7 Thefollowing examples further illustrate this invention. The invention isnot limited to the subjects matter of these examples.

EXAMPLES I TO 6 AND COMPARATIVE 8 The pulp-water suspension is pouredinto a porous speaker cone mold to form a cone-shaped wet paper product.Then, the paper is dried to give a speaker cone.

EXAMPLES 1 O 3 Table 2 shows the amount of each ingredient added and thenon-flammability and sound-reproducing char- Speaker cones are producedin the following way. acteristics of the speaker cones produced.

After 100 parts of bleached sulfate fibers of soft As clearly shown inTable 2, speaker cones of this inwood is beaten, the followingingredients are added vention have good non-flammable property andexthereto to make a fiber-water suspension (fiber content tremely lowpropagation velocity, thereby contributing 0.05 weight percent). gooddirectivity of the sound.

Further, FIG. 1 shows the relationship between the frequency and thesound pressure level of speaker Pans cones in this invention. As clearlyshown in FIG. 1, direct black dye 3 speaker cones of this invention haveimproved sound Paper Strengthcnmg characteristics in the high frequencyregion and give a (urea-formaldehyde resin) 3 chlorinated polymer", 30substantially flat sound pressure level in the middle freantimonytrioxide quency regi n aluminum sulfate 5 coagulating agent (TrademarkAquoflock) 008 TABLE 2 Addition amount (parts) fibers dye paper firefixing agent coagulating strengthening retardant agent agent N.B.K,,direct urea- CPE-l/ aluminum Aquoflock (20SR) black fonnaldehyde panssulfate 305 Example l 100 dye resin SbgOu/ O 5 parts 0.08 parts parts 3parts 3 parts parts H H H CPEZ H H Example 2 3O/Sb O 20, parts H H HCPRl H H Example 3 3(J/Sb O; 20, parts H H H CPP 2 H H Example 4 3O/SbO; 20, parts H H H CR4 H H Example 5 3O/Sb O 20, parts H H H CR4 H HExample 6 3O/Sb O 20, parts fiber content weight/area oxygen indexpropagation frequency in water velocity charactersuspension isticsExample 1 0.05% 30 g/m 32 200 m/sec solid line in FIG. 1

Example 2 31 250 Example 3 33 210 Example 4 3] 250 Example 5 32 200Example 6 30 240 Addition amount (parts) fiber dye paper fire fixingcoagulating strengthening retardant agent agent agent N.B.K,, directureaphosphoaluminum Aquoflock Comparative (20SR) black formaldehydenitrile sulfate 305 Example 1 100 dye resin chloride 5 parts 0.08 partsparts 3 parts 3 parts parts Comparative polyvinyl Example 2 chloride 50parts Comparative none Example 3 fiber content weight/area oxygen indexpropagation frequency in water velocity character suspension isticsComparative 0.05% 30 g/m 23 900 m/sec dotted line Example 1 in FIG. 1Comparative 21 950 Example 2 Comparative 18 I000 TABLE 2 ContinuedAddition amount (parts) fixing agent coagulating agent Example 3 Note:N.B.K,, bleached sulfate pulp of soft wood SR drainage rate Theembodiments of the invention in which an exclusive property or privilegeis claimed are defined as follows:

1. In a loudspeaker of the type which comprises a speaker diaphragm orcone adapted to generate sonic and/or subsonic vibrations in response toan electrical signal, the improvement which comprises: said diaphragm orspeaker cone is made of cellulose fiber paper containing uniformlydistributed therein l from 10 to 50 parts by weight of particles ofchlorinated polyolefin having a molecular weight of from 500 to 40,000and a chlorine content of from 40 to 75 percent by weight and (2) from 5and 40 parts by weight of particles of antimony trioxide, the amounts of(l) and (2) each being based on 100 parts by weight of cellulosicfibers, whereby said diaphragm or speaker cone is non-flammable.

2. A loudspeaker as claimed in claim 1, in which the particles of (1)and (2) each having a particle size in the range of from 80 mesh to 300mesh.

3. A loudspeaker as claimed in claim 2, in which the amount of (l is to40 parts by weight and the amount of (2) is 10 to parts by weight, eachper 100 parts by weight of fibers.

4. A loudspeaker as claimed in claim 1, in which the paper also contains(3) 0.1 to 5 parts by weight of paper strengthening agent, (4) l to 5parts by weight of fixing agent, and (5) 0.01 to 0.1 part by weight ofcoagulating agent, each per 100 parts by weight of fibers.

5. A loudspeaker according to claim 1 wherein said chlorinatedpolyolefin is chlorinated polypropylene.

6. A loudspeaker according to claim 1 wherein said chlorinatedpolyolefin is chlorinated polyethylene.

7. A loudspeaker according to claim 1 wherein said chlorinatedpolyolefin is chlorinated natural or synthetic rubber.

8. A loudspeaker according to claim 1 wherein said chlorinatedpolyolefin is a mixture comprising at least two components selected fromthe group consisting of chlorinated polyethylene, chlorinatedpolypropylene and chlorinated natural or synthetic rubber.

9. In a loudspeaker of the type which comprises a speaker diaphragm orcone adapted to generate sonic and/or subsonic vibrations in response toan electrical signal, the improvement which comprises: said diaphragm orspeaker cone is made of cellulose fiber paper containing uniformlydistributed therein 1) from 10 to 50 parts by weight of particles ofbromine containing chlorinated polyolefin having a molecular weight offrom 500 to 40,000, a chlorine content of from 10 to 30 percent byweight and a bromine content of from 60 to percent by weight, and (2)from 5 to 40 parts by weight of particles of antimony trioxide, theamounts of (l) and (2) each being based on parts by weight of cellulosicfibers, whereby said diaphragm or speaker cone is nonflammable.

* l l l UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OFCORRECTION PATENT NO. 3 907 0 3 DATED September 23, 1975 |NV ENTOR(S)Masahiko Nakazawa et a1 It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 9, line 23; change "5 and 40" to 5 to 40.

Signed ahcl Sealed this twentieth D y of January 1976 [SEAL] Attest.

RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner uj'latentsand Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OFCORRECTION PATENT NO. 3 907 0 3 DATED September 23, 1975 lN\/ ENTOR(S)Masahiko Nakazawa et al It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 9, line 23; change "5 and 40" to 5 to 40.

Signed ahd Sealed this twentieth D y f Jan ary 1976 [SEAL] Arrest:

RUTH C. MASON Alresn'ng Officer C. MARSHALL DANN Commissioner oj'Patentsand Trademarks

1. IN A LOUDSPEAKER OF THE TYPE WHICH COMPRISES A SPEAKER DIAPHRAGM ORCONE ADAPTED TO GENERATE SONIC AND/OR SUBSONIC VIBRATIONS IN RESPONSE TOAN ELECTRICAL SIGNAL, THE IMPROVEMENT WHICH COMPRISES: SAID DIAPHRAGM ORSPEAKER CONE IS MADE OF CELLULOSE FIBER PAPER CONTAINING UNIFORMLYDISTRIBUTED THEREIN (1) FROM 10 TO 50 PARTS BY WEIGHT OF PARTICLES OFCHLORINATED POLYOLEFIN HAVING A MOLECULAR WEIGHT OF FROM 500 TO 40,000AND A CHLORINE CONTENT OF FROM 40 TO 75 PERCENT BY WEIGHT AND (2) FROM 5AND 40 PARTS BY WEIGHT OF PARTICLES OF ANTIMONY TRIOXIDE, THE AMOUNTS OF(1) AND (2) EACH BEING BASED ON 100 PARTS BY WEIGHT OF CELLULOSICFIBERS, WHEREBY SAID DIAPHRAGM OR SPEAKER CONE IS NON-FLAMMABLE.
 2. Aloudspeaker as claimed in claim 1, in which the particles of (1) and (2)each having a particle size in the range of from 80 mesh to 300 mesh. 3.A loudspeaker as claimed in claim 2, in which the amount of (1) is 20 to40 parts by weight and the amount of (2) is 10 to 30 parts by weight,each per 100 parts by weight of fibers.
 4. A loudspeaker as claimed inclaim 1, in which the paper also contains (3) 0.1 to 5 parts by weightof paper strengthening agent, (4) 1 to 5 parts by weight of fixingagent, and (5) 0.01 to 0.1 part by weight of coagulating agent, each per100 parts by weight of fibers.
 5. A loudspeaker according to claim 1wherein said chlorinated polyolefin is chlorinated polypropylene.
 6. Aloudspeaker according to claim 1 wherein said chlorinated polyolefin ischlorinated polyethylene.
 7. A loudspeaker according to claim 1 whereinsaid chlorinated polyolefin is chlorinated natural or synthetic rubber.8. A loudspeaker according to claim 1 wherein said chlorinatedpolyolefin is a mixture comprising at least two components selected fromthe group consisting of chlorinated polyethylene, chlorinatedpolypropylene and chlorinated natural or synthetic rubber.
 9. In aloudspeaker of the type which comprises a speaker diaphragm or coneadapted to generate sonic and/or subsonic vibrations in response to anelectrical signal, the improvement which comprises: said diaphragm orspeaker cone is made of cellulose fiber paper containing uniformlydistributed therein (1) from 10 to 50 parts by weight of particles ofbromine containing chlorinated polyolefin having a molecular weight offrom 500 to 40,000, a chlorine content of from 10 to 30 percent byweight and a bromine content of from 60 to 80 percent by weight, and (2)from 5 to 40 parts by weiGht of particles of antimony trioxide, theamounts of (1) and (2) each being based on 100 parts by weight ofcellulosic fibers, whereby said diaphragm or speaker cone isnonflammable.